In recent years considerable interest has been shown in ground fault circuit interrupter (GFCI) devices that provide additional protection to humans against electrical shock which may occur because of faults in electrical equipment and in electrical supply and distribution systems. GFCI protection devices have been constructed in a form suitable for mounting in the conventional circuit breaker panel box at the input to the electrical distribution system of a residence, for example. GFCI protection devices also are provided in the form of a duplex receptacle model which replaces the conventional two receptacle electrical outlet commonly mounted in a box at the lower portion of a wall. The receptacle model GFCI commonly provides two electrical outlet receptacles, and also houses the GFCI electronics and circuit breaker means for detecting a fault condition and for interrupting the supply circuit upon detection of a fault condition.
At the present time the installation of many duplex receptacle model GFCI devices is in the nature of a retrofit of existing receptacles and therefore must physically fit within existing standard mounting boxes. Because the present standard mounting boxes were made in a size to accomodate only the two plug receptacles and the necessary wire connections thereto, the space available in a box is quite restricted for accommodating a receptacle model GFCI having included therewith the electronic fault detecting circuitry and circuit breaker. This space limitation has resulted in considerable difficulty in the design and manufacture of receptacle model GFCI devices and has appreciably contributed to the cost of the devices.